Generally, there is a PCA (Power Calibrating Area) on a recordable disc. After the recordable disc is loaded into an optical disc burner for data writing, an optical pickup of the optical disc burner is moved to the PCA for executing an OPC procedure (Optimal Power Calibrating procedure). The OPC procedure is for generating an optimal write power, and then the optical disc burner can process the data writing to the recordable disc according to the optimal write power.
It is understood that data is recorded on spiral tracks of the recordable disc. In another word, the data must be encoded by a control chip of the optical disc burner first, and then the optical disc burner can drive a laser diode of the optical pickup to alternatively generate marks and non-marks on the spiral tracks of the recordable disc according to the signals of the encoded data. The non-marks recorded on the recordable disc are defined as Lands, and the marks are defined as Pits. Accordingly, when the OPC procedure is executed, the optical disc burner can drive the optical pickup to generate a test pattern constructed by a plurality of Lands and Pits.
FIG. 1 is a diagram illustrating a write strategy of a DVD recordable disc. Because the thermal diffusion may cause the actual length of the Pit 10 greater than a designed value, for making the length of Pit 10 (nT, n=3˜11) more accurate, the rising edge of a driving signal derived by the laser diode is designed to delay by a front-edge delay time (tn1), and the falling edge is designed to advance by a rear-edge advance time (tn2). Moreover, an overdrive power (Po) is designed to superpose to a write power (Pw) at the initial stage and the later stage of the formation of the Pit 10.
As depicted in FIG. 1, the front-end overdrive power (Po), having a front-end overdrive time (tn3), is superposed to the write power (Pw) and initiated at the rising edge of the driving signal. The rear-end overdrive power (Po), having a rear-end overdrive time (tn4), is superposed to the write power (Pw) and ended at the falling edge of the driving signal. By using a 3T Pit as an example, t31 is referred as the front-edge delay time of the 3T Pit; t32 is referred as the rear-edge advance time of the 3T Pit; t33 is referred as the front-end overdrive time of the 3T Pit; and t34 is referred as the rear-end overdrive time of the 3T Pit. Generally, the nT Pit 10 (n=3˜11) may have different values of the front-edge delay time (tn1), the rear-edge advance time (tn2), the front-end overdrive time (tn3), and the rear-end overdrive time (tn4), wherein these front-edge delay time (tn1), the rear-edge advance time (tn2), the front-end overdrive time (tn3), and the rear-end overdrive time (tn4) are together defined as a timing parameter set of a write strategy.
Generally, a recordable disc can be distinguished by reading the manufacture ID and the disc ID recorded on the recordable disc. Because different recordable discs, released by different manufacturers or released by the same manufacturer but having different dyes on the data layer of the recordable disc, have different write strategies, therefore, all the recordable discs released on the market must be collected and to be processed to find their corresponding parameters by using a verifying procedure. The verifying procedure is referred as a process of adjusting the overdrive power (Po) and the timing parameter set according to each manufacture ID and disc ID, and then storing the adjusted overdrive power (Po) and the adjusted timing parameter set to a read-only memory (ROM) of the optical disc burner. In another word, when a recordable disc is loaded into the optical disc burner for data writing, the optical disc burner can obtain the overdrive power (Po) and the timing parameter set from the read-only memory (ROM) according to the manufacture ID and the disc ID recorded on the track of the loaded recordable disc, and then the optical disc burner defines a write strategy (with uncertain write power) of the recordable disc according to the overdrive power (Po) and the timing parameter set. The write strategy is then used on the PCA for the OPC procedure. Alternatively, if the optical disc burner cannot find a matched manufacture ID or disc ID in the read-only memory (ROM) when the recordable disc is loaded, a standard overdrive power (Po) and a standard timing parameter set will be provided to the optical disc burner for defining a write strategy (with uncertain write power), and the write strategy is then used on the PCA for the OPC procedure.
The OPC procedure is to find the optimal write power (Pw) for combining the overdrive power (Po) and the timing parameter set to define the write strategy. In other words, the OPC procedure is for generating a plurality of test patterns on the PCA via providing a plurality of different write powers to the write strategy. The optical disc burner can obtain an optimal write power through measuring these test patterns, and then defines a write strategy according to the optimal write power (Pw), the overdrive power (Po), and the timing parameter set. The write strategy is then used by the optical disc burner for generating Pits and Lands with different time lengths on the program area of the recordable disc.
Conventionally, the overdrive powers (Po) and the timing parameter sets of write strategies for all the recordable discs released on the market are adjusted and stored in the read-only memory (ROM) of the optical disc burner before the optical disc burner is published to the market; and the OPC procedure executed on the PCA is only used for generating an optimal write power.
However, if a specific recordable disc, which is already released on the market, requires some modifications made by the same manufacture, the overdrive power (Po) and the timing parameter set which is used for the original recordable disc and stored in the read-only memory (ROM) of the optical disc burner may not be useful to the write strategy of the modified recordable disc. If using the original overdrive power (Po) and the original timing parameter set to the modified recordable disc, a poor write quality or even a fail data reading to the recorded disc may be resulted in. If using a standard overdrive power (Po) and a standard timing parameter set to a recordable disc when the disc ID of the recordable disc cannot be contained in the read-only memory (ROM) of the optical disc burner, the poor write quality may be still resulted in. Therefore, providing a dynamically adjusting method for an overdrive power (Po) and a timing parameter set of a recordable disc is the main purpose of the present invention.